A Bismarck man accused of having sex with a 14-year-old girl in an apartment building stairwell has pleaded not guilty to felony gross sexual imposition.

Authorities say police officers encountered 19-year-old Christopher Vandermeer and the girl on Oct. 28 after receiving a tip. The Bismarck Tribune reports (http://bit.ly/SxukOy ) that Police Detective Mark Gaddis testified Tuesday that the girl told him she and Vandermeer had been chatting online and texting for about a year.